Cleave Gem gets no benefit for Quality past 1%

As the title says, the Cleave Skill Gem, does not have any change for quality after the very first %.

That is, it does change when going from 0 to 1% Quality, but does not change when going from 1% to 23% Quality.

Expected behaviour is that it should change when reaching 20% Quality in some way, presumably that the current effect at 1% should actually be reached at 20% instead.

I have only verified this being the case on the trade website, but see no reason it wouldn't also apply in-game.